Background: The aim of this study was to analyze learning curves and competency gains of novice vascular trainees when performing open aortic repair in a simulation-based environment. Methods: This was a prospective study of 16 vascular trainees performing infrarenal open aortic repair on an inanimate abdominal aortic aneurysm simulator with pulsatile pressure and flow. Each participant performed 4 procedures as a primary surgeon while getting structured feedback by a supervising experienced vascular surgeon. All sessions were video recorded and were anonymously and independently assessed by 3 rater-trained experts on an online platform using the newly validated open abdominal aortic aneurysm repair of technical expertise assessment tool. All supervisor interferences and procedure time was noted. Results: Reliability between raters was excellent (intraclass correlation coefficient = 0.92). Participants' mean scores almost doubled during the course between the first (13.4, 95% confidence interval [CI], 6.8–20) and fourth session (29.8, 95% CI, 26.3–33.3) with a mean difference of 14.6 (P < 0.001). Supervisor interference also decreased significantly from mean 3.0 (95% CI, 1.5–3.6) in the first to 0.7 (95% CI, 0.4–1.0) in the fourth session (P = 0.004). Procedure time decreased with a mean of 24 minutes: from 81 min (95% CI, 71.8–90.3) to 57 min (95% CI, 51.1–63.2, P < 0.001). There was a significant negative correlation between procedure time and the Open Abdominal Aortic Aneurysm Repair of Technical Expertise score (Pearson's r = −0.72, P < 0.01). Only half of the participants passed the pass/fail score of 27.7 points during the course. Conclusions: Novice vascular trainees achieve skills and competencies in open aortic repair in a simulated setting with dedicated supervision and feedback and can become ready for supervised surgery on real patients. Learning rates are individual, and it is important to construct training programs with emphasis on proficiency and not merely attending a course.